1. Field of the Invention
This invention relates to an aluminum alloy, and more specifically to an alloy usable in an aluminum anode.
2. Description of the Prior Art
The use of aluminum alloys in batteries is well known. Aluminum is a preferred material for battery anodes because of its high energy content and low cost. However, problems with voltaic efficiency in protic solvents and coulombic inefficiency have prevented wide commercial use of these aluminum anodes. See U.S. Pat. No. 3,513,031.
Aluminum-tin alloys have been studied for possible use as galvanic anodes in seawater, however, these alloys have produced very low efficiencies. See Keir et al, "Galvanic Corrosion Characteristics Of Aluminum Alloyed With Group IV Metals", Journal Of Electrochem. Soc., 114, (8), 777, 1967.
It is preferred that aluminum-air batteries have high voltage and high coulombic efficiency. However, one of these characteristics is usually sacrificed at the cost of the other characteristic. The use of gallium to increase voltage in aluminum anode alloys is known. See U.S. Pat. No. 3,393,138. U.S. Pat. No. 4,150,204 discloses an aluminum alloy anode preferably containing 0.001 to 0.072 percent by weight of gallium used in seawater cells. The purity of aluminum is 99.997 percent. Alternatively the aluminum may have incidental impurities.
Many aluminum alloys incorporate tin in order to create higher galvanic currents. See U.S. Pat. Nos. 3,282,688, 3,368,952, and 3,189,486. U.S. Pat. No. 3,186,836 discloses an aluminum-tin alloy which contains less than 0.05 percent silicon and less than 0.1 percent iron.
U.S. Pat. No. 3,240,688 discloses an aluminum based alloy which contains 0.04 to 0.5 percent tin, 0.005 to 1.0 percent gallium. The tin is retained in solid solution to the maximum degree of 0.1 percent.
Canadian Pat. No. 863,864 discloses an aluminum based alloy which contains 0.04 to 0.5 percent tin; 0.001 to 0.1 percent boron, a lattice expander selected from the group consisting of magnesium, gallium, zirconium, bismuth, indium and mixtures thereof; 0 to 0.25 percent to transition metal, 0 to 0.10 percent silicon and 0 to 0.10 percent iron.
In spite of these prior disclosures, there remains a need for an aluminum anode alloy which produces high voltages, high coulombic efficiency and reduces gas blockage in the electrolyte passages.